Lubricating oil additive



United States Patent C) LUBRICATING 01L ADDITIVE William C. Hollyday, Jrt, Fanwood, N. 1., assignor to Esso Research and Engineering Company, a corporation of Delaware No Drawing. Application December 28,1953 Serial No. 400,782

7 Claims. (Cl. 252-34) This invention relates to new compositions of matter. It also relates to lubricating oil compositions. The invention particularly relates to lubricating oil compositions containing dissolved therein minor amounts of lubricating oil pour point depressant and to the oil-soluble pour point depressant material per se. More particularly, the invention relates to new compositions of matter which are soluble in oil and which have the desirable characteristic of depressing the pour point of lubricating oils when combined therewith. Still more particularly the invention relates to oil-soluble polymeric salts which are made by reacting a polyalkylene imine with fatty acids and to oil solutions of said reaction products.

In the past when lubricating oil manufactureres wished to prepare a product which would remain in a fluid state at low temperatures it was necessary to stringently refine the crude distillates used in preparing the lubricating oil fraction. A great deal of time and effort was spent in dewaxing the mineral oil fraction to obtain a low cold test oil. The presence of petroleum wax in a lubricating oil results in loss of fluidity at temperatures below the melting point of the wax since at these low temperatures wax crystallizes in long needle-shaped crystals which interlock and thereby entrap the oil and prevent free flowing. However, there has been developed a series of synthetic materials which modify the structure characteristics of wax crystals. When small amounts of these materials are placed in a lubricating oil containing wax, the crystals that form at low temperatures are not of a long needlelike variety previously experienced and the oil remains free to flow at low temperatures. The temperature at which an oil containing wax loses its properties of free flow is called the pour point of the oil. Hence these synthetic materials designed to lower this temperature are called pour point depressants. It is a novel material of this type, that is, one having the property of depressing the pour point of wax-containing oil, with which this instant invention is concerned.

It has now been found, and forms the object of this invention, that oil soluble materials having the desirable characteristic of depressing the pour point of lubricating oils with which they are combined, can be prepared by contacting an alkylene imine copolymer of suitable molecular weight with a fatty acid.

Heretofore, known polymeric pour depressants have been characterized by having the structure of a long main chain to which are attached numerous side chains. Usually, a long chain of carbon atoms, such as methylene groups, for the main portion, or backbone of the polymer molecules, side chains being for the most part long alkyl groups. The side chains may be attached to the main chain through ester, ether, or other groupings, and the main chain may also contain such groupings as connecting links. Heretofore, all linkages in the polymer molecule have involved primary valence bonds only, and no secondary bonds or ionized regions have been present. In order to build up the desired structure of the poly- "ice mer molecule complicated chemical reactions have been carried out using carefully purified reactants and critical reaction conditions.

In the instant invention, however, the side chains which result in pour point depressing activity are connected to the main chain of the molecule, not through primary valence bonds, but through ionic linkages.

The structure of the molecule of the instant pour point depressant may be represented as follows:

In the formula above, p represents the degree of polymerization of the alkylene imine and may vary from 3 to 150. R represents an alkyl group which is the alkyl radical of the fatty acid used. R may be saturated or unsaturated, with the former preferred, and may contain from about 5 to about 19 carbon atoms. X represents an alkylene group and may be a methylene group, which is preferred, an ethylene group, a propylene group or the like. In the preferred embodiment of this invention, a polyethylene imine is reacted with a fatty acid having from about 6 to about 20 carbon atoms per molecule. The molecular weight of the polyethylene imine is such that the final product has an intrinsic viscosity of about 0.05 to 2.0 when measured as a solution in toluene.

The surprising and unexpected features of the present invention are two: one, that the salt of an alkylene imine polymer is oil-soluble, and two, that such salts have pour point depressing potency. It is believed that this is the first discovery of such unique features of materials of this yp The invention will be more clearly explained by reference to the following examples, which are of illustrative nature only and are not to be taken as limiting the inventive concept.

EXAMPLE 1 A solution of 5.6 grams (0.130 equivalent) of ethylene imine polymer (of a molecular weight such that a 50% solution in water had a viscosity of about 850 poises at 25 C.) in an equal weight of water was charged to a flask and 250 ml. of benzene were added. The mixture was refluxed with provision for removing the water which distilled over with the benzene. After all the water had been removed, 28.0 grams (0.127 moles) of coconut acids (R=C having an average molecular weight of 220 were added. The tough gelatinous polyethylene imine which had precipitated from the benzene dissolved almost instantly. The clear benzene solution containing the oil-soluble polymeric salt was evaporated to dryness. The yield was theoretical (33.6 grams).

The product was readily soluble in oil. A concentrate containing 20% polymeric salt and of an extracted lubricating oil wasmade up to be used for making more dilute oil blends.

The oil concentrate of the above example was blended in various percentages in an extracted Mid-Continent SAE 20 base stock having a pour point of +15 F. ASTM pour point data of the blends are set out in Table I below. Data on the polymer itself and on the fatty acid blends are included for purposes of comparison.

3 Table I ASTM POUR POINTS OF BLENDS OF POLYETHYLENE IMINE-FATTY ACID PRODUCT IN 01L It will be seen from the data above that in only 0.01 wt. percent concentration, the material prepared in accordance with the instant invention lowered the pour point of the oil 25 F. This is an outstanding potency.

EXAMPLE 2 A blend containing 50 wt. percent of the polyethylene imine-fatty acid product from Example 1 and 50 wt. percent wax naphthalene condensate (made by alkylating naphthalene with a chlorinated wax) was tested as .a pour depressant in the same test oil as used for the examples in Table I, with the results set forth below.

Table II POUR DEPRESSANCY OF POLYETHYLENE IMINEzFTTY 4011. D X- APH A E E n Nsar Wt. Percent Additive-.. ASTM Poul Point, F

The amount of the pour depressant in accordance with this invention that is blended with the lubricating. oil to lower the pour point thereof will ordinarily vary fiom about 0.005% by weight to about 10.0% by weight, the percentage being based on the weight of the total composition. A preferred range, and one being operable in most base stocks, is from about 0.01% to 3.0% by weight. centratcs of the lubricating oil additive materials for ease in handling and general economy. Ordinarily these concentrates are prepared by blending from about 10.0% to about by weight of the additive with the mineral oil base. The lubricating oil manufacturer then blends the desired amount of these concentrates in his base stock to prepare the finished product. The materials of the instant invention are adapted favorably to such use.

Lubricating oil compositions containing the materials prepared as described above may also contain other additive materials such as other pour point depressants, viscosity index improvers, oxidation inhibitors, detergent inhibitors, sludge dispersants and the like. Compatibility of the instant additives with other additives has been found to be generally excellent.

To summarize briefly, the instant invention relates to pour point depressant materials, their method of manufacture, and lubricating oils containing a minor, but pour point depressing amounts of such materials. The invention particularly relates to reaction products that are electrolytes and are formed by reacting together an alkylene imine polymer of a molecular weight within a range so that the product has an intrinsic viscosity of about 0.05 to 2.0 when measured in toluene with a fatty acidcontaining about 6 to 20 carbon atoms. Specifically preferred materials are the reaction products of ethylene imine polymers with fatty acids containing about -8 to about 18 carbon atoms.

What is claimed is:

1. A product formed by reacting together an alkylene It has been found advantageous to prepare conimine polymer with fatty acid, said product having the formula where X is an alkylene group selected from the class consisting of methylene, ethylene and propylene, p represents the degree of polymerization of said alkylene imine and is an integer in the range of 3 to the degree of polymerization being such that the final product has an intrinsic viscosity in the range of 0.05 to 2.0 when measured as a solution in toluene, and R is the alkyl radical of said fatty acid and contains in the range of 8 to 18 carbon atoms.

2. A product formed by reacting together an alkylene imine polymer with fatty acid, said product having the formula I c R where X is a methylene group, p represents the degree of polymerization of said alkylene imine necessary to give a polymer having a molecular weight such that a 50% blend in water has a viscosity of about 850 poises at 25 C., and R is the alkyl group of said fatty acid, said fatty acid being derived from coconut oil and R averaging about 12.5 carbon atoms.

3. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and about 0.005

to 10.0%, by weight, based on the total composition of a product in accordance with claim 1.

4. A lubricating oil composition comprising a major proportion of a mineral lubricating oil and about 0.01 to 3.0% by weight, based on the total composition, of the product of claim 2.

5. A product formed by reacting together an alkylene imine polymer selected from the group consisting of polyethylene imine, polypropylene imine, and polybutylene imine with a fatty acid containing in the range of 8 to 18 carbon atoms, the degree of polymerization of said polyalkylene imine being such that said product has an intrinsic viscosity of about 0.05 to 2.0 when measured as a solution in toluene, the radical of said fatty acid being connected to each repeating unit of said polyalkylene imine through ionic linkages forming thereby a salt.

6. A product formed by reacting together an alkylene imine polymer with a mixture of fatty acids derived from coconut oil, said product having the formula i=0 lit degree of polymerization being such that the final product 1 hasan intrinsic viscosity in the range of 0.05 to 2.0

5 when measured as a solution in toluene, and R is the alkyl radical of said fatty acids containing an average of about 12.5 carbon atoms.

7. A product formed by reacting together an alkylene imine polymer with a mixture of C, to C fatty acids, 5 said product having the formula where X is an alkylene group selected from the class 15 consisting of methylene, ethylene and propylene, p rep- 6 resents the degree of polymerization of said alkylene imine and is an integer in the range of 3 .to 150, the degree of polymerization being such that the final product has an intrinsic viscosity in the range of 0.05 to 2.0 when measured as a solution in toluene, and R is the alkyl radical of said fatty acids containing an average of about 12.5 to 13.5 carbon atoms.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A PRODUCT FORMED BY REACTING TOGETHER AN ALKYLENE IMINE POLYMER WITH FATTY ACID, SAID PRODUCT HAVING THE FORMULA
 3. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OF A MINERAL LUBRICATING OIL AND ABOUT 0.005 TO 10.0% BY WEIGHT, BASED ON THE TOTAL COMPOSITION OF A PRODUCT IN ACCORDANCE WITH CLAIM
 1. 